The present invention relates to systems and methods for extending the life of fresh and/or perishable food products using automated humidification systems. The invention relates particularly to the use of automated humidification systems that release water vapor or droplets into various environments for storage of fresh or perishable products.
To maintain the freshness and desirable appearance of fresh products, such as perishable foods displayed in a merchandising case or display counter in a supermarket, or produce or plant materials housed in a storage facility, the produce must be kept in an environment that is cool and moist. The amount of moisture must be carefully regulated to maintain the quality and storage-life of various perishable products. For example, dehydration of fresh produce results in spoilage, an unattractive product appearance and reduced salability. Too much moisture may result in excess water retention, producing an undesirable appearance and increased susceptibility of the products to bacterial or fungal growth.
Several systems have been developed for hydrating fresh food items. Automated fresh produce hydration systems are described, for example, in the following U.S. Patents, which are incorporated herein by reference in their entireties: U.S. Pat. Nos. 4,808,303; 5,470,970; and 5,651,502. These patents describe various approaches to hydrating fresh food. In all of them, water is conveyed to a plurality of spray or nozzle heads designed to deliver moisture in the form of a mist or a fog or vapor to food items displayed or stored below the spray heads. These systems utilize a regulator, solenoid valve and pressurization tank to adjust and maintain the water pressure.
Many conventional humidification systems utilize air pressure to atomize water, forming a vapor which is then distributed into the environment to regulate the relative humidity. To atomize water, conventional systems employ air pressure in combination with pressurized water to generate a pressure head sufficient to force the air/water mixture through the spray head or nozzle assembly to achieve a very fine water vapor. The water pressure determines the volume of water dispersed into the environment through the spray heads. The interval and duration of water vapor release is regulated through a timer, sensor or control device that activates a compressor, which pressurizes the system as described above.
An inherent problem with humidification and misting systems is the xe2x80x9cstreamingxe2x80x9d of water from the spray heads or nozzles at the end of a pressurization and water atomization cycle, which is due to residual pressure in the water line. This streaming of water is very undesirable because excess water adversely affects the quality and storage life of the products immediately below. To compound the problem, the greater the water pressure of the system, as required for a large storage facility, the greater the streaming effect. To remedy this problem, conventional systems reduce the water pressure down to a range of 2 to 5 psi by means of a regulator and solenoid valve system at the end of a pressurization cycle. Additionally or alternatively, these systems often require a bladder tank on the air line to serve as a capture reservoir for surplus air pressure once the compressor has shut off at the end of a cycle. By reducing the water and/or air pressure, the system pressure drops accordingly, alleviating the force that causes the water to release or stream from the spray heads.
Furthermore, to achieve proper atomization of water, conventional systems require a carefully balanced ratio of air to water pressure, which must be tailored to the specific application. For example, a seafood display case in a supermarket requires low air and water pressure to deliver a small volume of water vapor and maintain a predetermined relative humidity, whereas a large produce storage facility requires higher air and water pressure to deliver a large volume of water and maintain a desired relative humidity. In all instances, the volume of water vapor required to achieve the desired relative humidity for each particular application requires a careful balancing of the air to water pressure ratio. This individualized xe2x80x9ctuningxe2x80x9d of the system is required to meet the specific requirements of the particular environment in which the humidification system is employed. These systems have many disadvantages.
Another deficiency of conventional humidification and misting systems, specifically systems employed in large storage facilities, is blockage of the misting nozzles, water and air lines due to freezing. In general, the majority of the systems installed in storage facilities are for cold storage, which typically require ambient air temperatures of 34xc2x0 F. To achieve and sustain a uniform 34xc2x0 F. ambient temperature, it is common for the nozzle assemblies and the air and water lines to be exposed to temperatures ranging from 20-25xc2x0 F. due to their proximity to refrigeration systems. As a result, water freezes in atomization nozzles and water lines, as well as water accumulated in air lines through condensation. The present invention remedies this problem by providing a system incorporating a heated conduit assembly. The heated conduit assembly is incorporated into humidification systems immediately upstream of the atomization nozzles and maintains the temperature of the atomization nozzles and associated air and water lines above the freezing point to prevent blockage of the system.
The present invention is therefore directed to an automated humidification system that is more effective and efficient, less expensive to manufacture and install, and more flexible in its application than automated humidification systems currently used by industry. These features will be further discussed herein and represent a significant advance in this field.
The present invention provides improved systems and methods for the hydration of environments in which perishable products are displayed and/or stored. Systems of the present invention are especially suitable for use in connection with the storage and display of fresh and/or perishable food items, including fresh fruits and vegetables, meat, seafood, dairy, tobacco and floral items. Notably, the inventive systems may be employed in various storage environments such as display cases, walk-in storage rooms, greenhouses and large-scale storage facilities, or other such environments.
A particular aspect of the present invention is directed towards systems, methods and
kits for providing consistent humidification while effectively eliminating the problem of xe2x80x9cstreaming.xe2x80x9d Streaming or dripping, as used herein, is defined as water escaping from atomization nozzles at the end of a pressurization and atomization cycle. Streaming is effectively controlled by one or more drawback valves incorporated into automated humidification systems. At the end of a pressurization and atomization cycle, said drawback valve generates negative water pressure in associated water lines and components, thereby drawing the water head in a retrograde direction and holding said water head in place until the next pressurization cycle. Negative water pressure generated by drawback valve effectively prevents water streaming from atomization nozzle assemblies. Furthermore, residual air pressure in associated air distribution lines fully atomizes any residual water in associated water lines and components, thereby displacing any residual water that may be inclined to stream onto products below.
The present invention provides a more compact and self-contained system that utilizes fewer parts, and therefore is less expensive to manufacture. The present invention eliminates the traditional regulators, pressure tanks and solenoid valve assemblies required to control water-pressure, as well as bladder tanks and regulator valves for regulating air pressure, while more effectively controlling the problem of streaming.
Systems of the present invention are simpler and less expensive to install, operate and maintain. In conventional systems, the water regulator is much larger and installed in a location away from the nozzle heads, whereas the present invention may optionally utilize a miniature water regulator located in proximity to the nozzle assembly. As mentioned above, the present invention eliminates the traditional water regulators, pressure tanks and solenoid valve assemblies, and air bladder tanks and air regulator valves, as well as the electrical connections required to install them.
Embodiments of the present invention are more versatile by utilizing a standard atomization nozzle assembly which may be used for a wide variety of applications. This greatly simplifies and lowers the cost of installation by eliminating the necessity of determining the correct nozzle assembly for each particular application. Additionally, a variety of nozzle assemblies may be used in connection with the present invention to achieve an even wider range of applications.
The present invention reduces the time required to disperse atomized water into the atmosphere. In contrast to conventional systems, the present invention requires a only a small drop in air pressure sufficient to activate the drawback feature of the drawback valve, which holds the water head inches from the atomization nozzle. Upon activation of a pressurization and atomization cycle, the system is poised to disperse the atomized water immediately.
The humidification systems of the present invention, incorporating a drawback valve and, optionally, a miniature water regulator eliminates manually balancing the air to water pressure ratio for each particular application, as currently required in conventional systems. Drawback valves incorporated into humidification systems of the present invention, having an air pilot 2-way poppet design, automatically maintains a pressure differential of 10-12 psi air pressure over water pressure. As the water pressure varies, the drawback valve adjusts accordingly to maintain the necessary air pressure for proper atomization of water at the nozzle assembly. The present invention thereby eliminates the need to manually adjust the air pressure to maintain proper atomization.
Embodiments of the present invention are capable of operating at very high water pressure conditions without the use of traditional water regulators, solenoid valves and pressure tanks. The present invention incorporating a drawback valve, and optionally, a miniature water regulator, is capable of operating at water pressures greater than or equal to 80-100 psi, resulting in a greater volume of water vapor released into the atmosphere. Furthermore, because the present invention incorporating a drawback valve, and optionally, a miniature water regulator, is capable of operating at higher water pressures, the inventive systems generate a finer mist or water vapor, i.e. water droplets having a relatively small median diameter, without the additional air and water components described above. Consequently, the fine water vapor or mist circulates in the atmosphere longer and is less prone to precipitate onto items being stored. These attributes are especially important in large applications, such as in walk-in coolers and in particular, large storage facilities, where the tremendous volume of air in the enclosed facility requires more water vapor to maintain a suitable relative humidity and temperature. Notably, even at these higher pressures, the current invention prevents streaming from atomization nozzle heads.
Embodiments of the present invention prevent blockage of the humidification system due to freezing water in the atomization nozzle assemblies and adjoining air and water lines. These components are typically installed in close association with refrigeration works to cool the water vapor in order to maintain a cold environment. The present invention provides a system incorporating a heated conduit assembly. The heated conduit assembly is incorporated into humidification systems immediately upstream of the atomization nozzles and maintains the temperature of the atomization nozzles, air and water lines above freezing to prevent blockage of the system.
Automated humidification systems of the present invention include one or more drawback valves, miniature water regulators and/or heated conduit assemblies operably connected through various distribution lines, electrical connections and communication links to compressed air and pressurized water sources, systems controls and atomization assemblies.
According to one preferred embodiment of the present invention, an automated humidification system comprises a drawback valve and miniature water regulator operably connected through various distribution lines, electrical connections and communication links to compressed air and pressurized water sources, systems controls and atomization assemblies. Such preferred embodiments may preferably be used in display cases, small storage facilities and ripening rooms.
According to another preferred embodiment of the present invention, an automated humidification system comprises a drawback valve and a heated conduit assembly operably connected through various distribution lines, electrical connections and communication links to compressed air and pressurized water sources, systems controls and atomization assemblies. Optionally, in yet another embodiment, the humidification system may additionally comprise a miniature water regulator. Such embodiments may preferably be used in storage facilities of all sizes.
The present invention also provides kits for retrofitting existing humidification systems for the hydration of environments in which perishable products are displayed and/or stored. Kits of the present invention comprise one or more drawback valve(s), miniature water regulator(s) and/or heated conduit assembly(ies), as well as any accessory components required for efficient installation, such as, but not limited to atomization nozzle assemblies, air and water lines, conduits, fittings, connectors, electrical connectors, and the like. Several of the aforementioned components may be pre-assembled, or alternatively, provided as individual components.